[sdiy] Expo Converter and Tempco

[Andre Majorel]

On 2006-11-10 11:14 -0800, James Patchell wrote:
> On 2006-11-10 08:35 -0800, sdiy at oveloe.com wrote:
>
> >We finally settled for the ENS-76 option 1 VCO as our base
> >design, it can be seen here
> >http://home.att.net/~synthsource/ens76/vco2.htm We're also
> >going to be building the expo converter from the same circuit
> >(it's the one I understand the most). But at this point, we
> >need tempcos, they mention tellabs q81 which is a 2k
> >3500ppm/degrees celcius (some say 3300ppm/...) precision
> >resistor. Which one is more precise, 3500 or 3300?

Ian pointed out that 3500 PPM/K is preferable because you can
always lower the tempco (by putting an ordinary resistor in
series).

> >Anybody has few (5-8) for sale or knows a place to get them for
> >less than 8$ each?
>
> Tel Labs is no longer really around (well, they are, but
> absorbed by somebody else...Vishay I think).  KRL also makes
> tempcos...somebody on the list just got a bunch made...but you
> need to order a min of 100 pieces or so from KRL if you are
> going direct.

All the links I've gathered on the subject :

- Digi-Key :

    - P1.0KCDCT-ND Panasonic-ECG ERA-S33J102V 1 k 3300 PPM/K 5%
      0.1 W SMD 0805 for 0.552 USD each.

	http://www.digikey.com/scripts/DkSearch/dksus.dll?PName?Name=P1.0KCDCT-ND&Site=US

    - P1.8KCDCT-ND Panasonic-ECG ERA-S33J182V 1.8 k 3300 PPM/K 5%
      0.1 W SMD 0805 for 0.552 USD each.

	http://www.digikey.com/scripts/DkSearch/dksus.dll?PName?Name=P1.8KCDCT-ND&Site=US

- Farnell sell the +3000 PPM/°C Meggitt LT300014T261K0J (order
  codes 732-278 and 1174-306).

    http://farnell.com/

- KRL Bantry Components, inc. make tempcos from +80 PPM/°C to
  +5000 PPM/°C.

    http://www.krlbantry.com/products/Precision/sect-312.htm

  If you order enough (several hundreds), they're not too
  expensive. CJ billed me 1.53 USD each for the 1 k.

- Micro-Ohm make tempcos from +1000 PPM/°C to +5100 PPM/°C.

    http://www.micro-ohm.com/temperature/temprecflm.html

- Precision Resistor Company, inc. have +3500 PPM/°C in stock.
  Other coefficients available.

    http://www.precisionresistor.com/ATST.HTM

- Weltronic distribute Precision Resistor Company products in
  Germany.

    http://www.weltronic.de/

-- 
André Majorel <URL:http://www.teaser.fr/~amajorel/>
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